First of all, if the domains are getting any remarkable traffic, that is the information that will really sell them. If people see you have neglected to share this data, they'll assume they're getting nothing and not worth investing in.
Also, suggesting possible uses for the domains would make them more attractive to someone wanting to develop them.
If it's getting no traffic and you cant think of a use for it, you cant do much more to market it, and it was probably a poor investment on your part.